Structural Organisation Of The Brainstem

Question 1

What is the brainstem made up of?

Answer 1

Medulla oblongata
Pons
Midbrain

Question 2

If the brainstem were to be cut in transverse sections what would the four areas seen be?

Answer 2

(Posterior to anterior)
Tectum (roof of ventricular system)
Ventricular system
Tegmentum (core of the brainstem)
Basal portion (most anterior)

Question 3

What are the three broad functions of the brainstem?

Answer 3

Connects the tracts to higher centres
Contains reflex centres
Houses nuclei of cranial nerves 3-12

Question 4

Where is the midbrain/ mesencephalon found?

Answer 4

Located between the Diencephalon and the pons

Question 5

Where is the cerebral aqueduct found?

Answer 5

The cerebral aqueduct is hollow and runs through the midbrain and connects the 3rd and 4th ventricles

Question 6

Which cranial nerves emerge from the midbrain?

Answer 6

Oculomotor (3)
Trochlear (4)

Question 7

What is the corpora quadrigemina?

Answer 7

It is a reflex centre that connects the midbrain to the hindbrain

Question 8

How is the corpora quadrigemina divided?

Answer 8

2 superior colliculi
2 inferior colliculi

Question 9

What reflexes are the superior colliculi responsible for?

Answer 9

Control reflex movements of the eyes, neck, and head in response to visual stimuli

Question 10

What reflexes are the inferior colliculi responsible for?

Answer 10

Control reflex movements of the head, neck and trunk in response to auditory stimuli

Question 11

Where is the red nucleus found?

Answer 11

It is a large subcortical structure in the ventral midbrain

Question 12

How is the red nucleus divided?

Answer 12

The red nucleus is cytoarchitectonically divided into two histologically distinct subregions

Question 13

What are the two regions of the red nucleus?

Answer 13

A magnocellular caudal region - large sparse neurones
Rostral parvocellular region - small and medium neurones

Question 14

What’s the role of the red nucleus?

Answer 14

It is a relay station
And integrates information
Issues subconscious motor commands concerned with muscle tone and posture

Question 15

Where does the red nucleus receive information from?

Answer 15

It contains various blood vessels and will receive information from the cerebrum and cerebellum

Question 16

Where is the substantia nigra?

Answer 16

It is found lateral to the red nucleus

Question 17

What does the substantia nigra do?

Answer 17

The melanin containing substantia nigra secretes dopamine to inhibit the excitatory neurones of the basal nuclei

Question 18

What is the difference between a healthy individuals and someone with Parkinson’s brain scan?

Answer 18

The Parkinson’s patient will lack dark spots (Dopaminergic neurones) as there is damage to the substantia nigra

Question 19

Where is the pons found?

Answer 19

The pons is found between the midbrain and medulla oblongata
Acts as a bridge?

Question 20

What are the two surfaces of the pons?

Answer 20

Anterior surface - large bulge (basilar pons)
Posterior surface - cerebellar peduncles (tegmentum)

Question 21

Where is the locus coeruleus found?

Answer 21

It is located within the dorsal wall of the upper pons, under the cerebellum in the caudal midbrain
It is also surrounded by the 4th ventricle

Question 22

What is the importance of the locus coeruleus?

Answer 22

This nucleus is one of the main sources of noradrenaline in the brain
It is composed of mostly medium sized neurones

Question 23

What is different about the locus coeruleus?

Answer 23

Melanin granules inside it contribute to it being coloured blue

Question 24

Which cranial nerves emerge from the groove between the medulla and pons?

Answer 24

6, 7, 8

Question 25

Which nuclei are associated with the pons?

Answer 25

Sensory and motor nuclei of cranial nerves 5, 6, 7, 8

Question 26

What are the two respiratory centres found in the pons?

Answer 26

Apneustic centre Pneumotaxic centre

Question 27

What is apneusis?

Answer 27

A disturbance of respiratory rhythm characterised by sustained gasping inhalation Increased Inspiratory effort

Question 28

What does the apneustic centre do?

Answer 28

It is thought to excite the inspiratory centre by gradually increasing the firing rate of inspiratory muscles

Question 29

What does the pneumotaxic centre do?

Answer 29

Prevents apneusis by promoting coordinated respiration

Question 30

Describe a little about the medulla oblongata

Answer 30

It connects to the pons superiorly Connects to the spinal cord inferiorly Contains long ascending and descending tracts to higher centres Allows brain and spinal cord to interact Coordinates complex autonomic reflexes Controls visceral functions

Question 31

What are the components of the anterior surface of the medulla oblongata?

Answer 31

Pyramids - contain corticospinal tracts Decussation of pyramids Olives - underlying olivary nuclei

Question 32

What are the two tubercles of the posterior aspect of the medulla oblongata?

Answer 32

Gracile tubercle Cuneate tubercle

Question 33

What is the reticular formation?

Answer 33

A set of interconnected nuclei that are located in the brainstem, hypothalamus and other regions

Question 34

What does the reticular formation do?

Answer 34

Reticular activating system for alertness Filter out repetitive or familiar stimuli it is inhibited by sleep, alcohol and drugs

Question 35

What are the distinct levels of the vertebral column?

Answer 35

Cervical Thoracic Lumbar Sacral Coccygeal

Question 36

What is important to remember about the cervical spine?

Answer 36

There are 7 cervical vertebrae but 8 cervical nerves! The first 7 exist superiorly to their vertebra while the 8th exists caudally

Question 37

How many vertebrae does each distinction have?

Answer 37

Cervical - 7 Thoracic - 12 Lumbar - 5 Sacral - 5 Coccyx - fused

Question 38

How many spinal nerves are there?

Answer 38

31 pairs 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal

Question 39

Where does the spinal cord end?

Answer 39

In adults around L1/2 In children closer to L3

Question 40

What is the name of the end point of the spinal cord?

Answer 40

The conus medullaris

Question 41

What projects from the conus medullaris?

Answer 41

The cauda equina (horses tail) This will contain the remaining spinal nerves that project to their corresponding vertebrae

Question 42

What are the denticulate ligaments?

Answer 42

They anchor the chord within the dural sac

Question 43

What is the filum terminale?

Answer 43

It is a fibrous band that extends from the conus medullaris to the periosteum of the coccyx

Question 44

What is the function of the filum terminale?

Answer 44

To fixate, stabilise and buffer the distal spinal cord from normal and abnormal cephalic and caudal traction

Question 45

What is the lumbar cistern?

Answer 45

The subarachnoid space in the lower lumbar spinal canal It is an enlargement of the subarachnoid space in the dural sac distal to the conus medullaris

Question 46

Where in the spinal cord is it suitable to take a lumbar puncture?

Answer 46

In adults between L3-L4 In children between L4-L5

Question 47

What is the organisations of white and gray matter in the body?

Answer 47

Spinal cord - grey inside, white outside Brain - white inside, grey outside

Question 48

How does the spinal cord look in cross section?

Answer 48

Butterfly shape of grey matter The grey matter is capped with substantia gelatinosa Surrounded by white matter

Question 49

What is a funiculus?

Answer 49

A bundle containing one or more tracts/ fasiculi

Question 50

What connects the two halves of the spinal cord?

Answer 50

They are connected by a gray commissure

Question 51

What are the three funiculi of the spinal cord?

Answer 51

Dorsal (posterior) Lateral Anterior (ventral)

Question 52

Where is the dorsal funiculus found?

Answer 52

Between the dorsal horn and the dorsal-median septum

Question 53

Where is the lateral faniculus found?

Answer 53

Between where the dorsal root enter and the ventral roots exit the spinal cord

Question 54

Where is the anterior faniculus found?

Answer 54

Between the anterior median fissure and the site where anterior roots exit

Question 55

What is the organisation of motor vs sensory fibres in the spinal cord

Answer 55

Motor function fibres are found more dorsally while sensory functions are found more centrally